Objective:To construct nucleic acid vaccine plasmid encoding severe fever with thrombocytopenia syndrome virus(SFTSV) nucleoprotein and to study its immunogenicity. Methods: SFTSV nucleoprotein gene was amplified by polymerase chain reaction (PCR). The PCR product was cloned into the expression vector pJW4303 to construct nucleic acid vaccine. The recombinant plasmid pJW4303-N was identified by sequencing and then transiently transformed into HEK293T cells to measure the nucleoprotein expression by Western blot. We immuned the BALB/c mice with pJW4303-N and used the blank vector pJW4303 as the control. The immunogenicity was detected by enzyme-linked immunosorbent method. Results: The recombinant SFTSV nucleoprotein expression vector pJW4303-N was successfully constructed and expressed in supernatants and cell lysates of HEK293T cells in vitro. Specific IgG antibodies and its subtype in mice were found by ELISA after immunization. IgG titer and its subsets in the serum of the BALB/c mice were significantly increased than those of the controls. IgG2a was significantly higher than IgG1. Conclusion: The nucleic acid vaccine of SFTSV nucleoprotein (pJW4303-N) has good immunogenicity. This research is the foundation for the further study of SFTSV nucleoprotein.